The goal of this laboratory is to examine and study diseases which have neuro-ophthalmic manifestations with the hope of understanding etiology, aiding diagnosis and staging of disease, and formulating and testing possible therapies. In this report I will concentrate on work in fibrous dysplasia and studies of various neuro-degenerative diseases which have characteristic oculomotor abnormalities. Fibrous dysplasia (FD) is a disease where normal bone is replaced with fibro-osseous tissue. In the polyostotic form, the anterior cranial base is frequently involved, including the sphenoid bones. The optic nerve passes through the sphenoid wing and is often found to be encased by FD on CT imaging. Controversy surrounds the management of fibrous dysplasia encased optic nerves, as optic neuropathy resulting in vision loss is the most frequently reported neurological complication. In collaboration with Dr. Michael Collins of the Dental Institute, a cohort of more than 60 patients with fibrous dysplasia have been examined and this cohort of patients continues to be followed longitudinally with neuro-ophthalmologic exams to track the natural history of this disease. Oculomotor control is distributed throughout the brain, and diseases differentially affecting parts of the brain can affect eye movements in different, and often specific ways. We have recorded eye movements in patients with neurodegenerative and genetic diseases to characterize their ocular motility disorder, to help make a specific diagnosis, correlate phenotype to genotype, stage disease progression, and to give insight into the processes underlying eye movement generation. Several examples appear below. In Gaucher disease a defect in the enzyme beta-glucosidase results in a metabolic byproduct being deposited in the liver and spleen, the bone marrow, and the brain. A subgroup (Gaucher type 3) presents with neurologic findings, including abnormal eye movements. Typically these patients have a horizontal supranuclear palsy and occasionally exhibit an oculomotor apraxia. An enzyme to treat this disease by replacing their deficient galactosidase activity is cerezmye. This has been used for the past 10 years with some efficacy in reducing liver-spleen and marrow involvement. However, the enzyme has had little effect on abnormal eye movements and neurologic symptoms. Perhaps this is due to the blood brain barrier preventing the enzyme from access to the brain. A new medication, OGT-918, is currently in a phase 1 drug trial and eye movements are felt to be crucial to studying its efficacy since abnormal eye movements are sometimes the only criteria differentiating patients with Gaucher type 3 from Gaucher type 1. Also eye movements are easily quantifiable and parametric. The new drug works by reducing the substrate for the defective enzyme. Eye movement recordings looking particularly at saccadic velocity are being performed as we clinically examine these patients, and they will continue to be followed longitudinally for disease progression. The recordings in patients taking the medication were performed before treatment, and all patients recruited have now made it past one year with recordings again performed while on the study medication. These eye movement results are being tabulated and preliminary results should be available within the next several months. The same medication, OGT-918, is also being studied as a treatment for patients with Niemann Pick type C disease, an inherited lipid storage disorder that affects the viscera and central nervous system. These patients have sphingomyelinase deficiency and they develop vertical supranuclear palsy. These patients are followed at Columbia University and come to NIH for their eye movement recordings. A protocol very similar to the one developed for Gaucher disease is ongoing. Again, saccadic eye movement parameters are a major outcome measure and all patients have now completed at least one year on the study drug. Results from this study are being studied and preliminary conclusions will be available within the next few months. Chorea-acanthocytosis is another rare neuro-degenerative disease. Recently, three patients with this disease have had eye movement recordings in my lab. The recordings demonstrated frequent square wave jerks, along with fractionation and slowing of their saccades which has not been previously reported. Hermansky Pudlak syndrome (HPS) is a rare autosomal recessive disorder with findings of oculocutaneous albinism, bleeding, and lysosomal ceroid storage. In a collaboration with Dr. William Gahl of NHGRI , we examined 27 patients with HPS and determined that most have congenital nystagmus and many have periodic alternating nystagmus, helping to further characterize the phenotype of this disease.